Today's telecommunication networks are characterized by specialization. This means that for every individual telecommunication service, at least one network exists that transports this service. Each of these networks was specially designed for that specific service and is often not at all applicable to transport another service. For example, advances in audio, video, and speech coding in compression algorithms in process in VLSI technology influenced the bit rate generated by a service and thus changed the service requirements for the network. In addition, resources which are available in one network generally cannot be made available for other networks. Thus, the need for a service independent network is evident based upon these disadvantages from existing networks.
Asynchronous transfer mode (ATM) is a communication method for use in a service independent network. With ATM, information for multiple service types, such as voice, video or data is conveyed in small, fixed-size cells. ATM networks are connection oriented. ATM technology combines the benefits of circuit switching (guaranteed capacity and constant transmission delay) with the benefits of packet switching (flexibility and efficiency for intermittent traffic). ATM technology provides a scalable bandwidth from a few megabytes per second (Mbps) to many gigabytes per second (Gbps). Because of it's asynchronous nature, ATM is more efficient that synchronous technologies, such as time-division multi-plexing (TDM).
ATM transfers information in fixed-size units called cells. Each cell contains 53 bytes. FIG. 1 is a diagram of the basic format of an ATM cell 10. ATM cell 10 contains a five byte header 11, which contains all of the information necessary for network management. ATM cell 10 also contains the payload 13, which is the remaining 48 bytes. Small fixed link cells are well suited for transferring voice and video traffic because such traffic is intolerant to the delay.
In reality, the ATM header 11 has a select number of bytes that are actually used, thereby resulting in a significant number of unused fields. Furthermore, a select number of bits per byte have fixed values. As there are 8 bits per byte, a total of 40 bits is sent in an ATM cell 10, standard format. The result of sending unused fields and sending bits with fixed values results in sending more bits than needed, which decreases the available bitrate. Thus, there is a need for a system and method to compress the size of the header cell so that more ATM header cells 10 can be sent in a shorter amount of time in an ATM network.
Thus, an unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.